Todd Grantham and One-Gap Nose Tackle in the 3-4
Pelini's 4-3 nose approach is similar to Grantham's 3-4 nose approach. In Pelini's scheme, the NT isn't a typical two-gap player; he's a DT lined up as a 1-tech instead of a 2-tech or a 3-tech. As a result, the NT doesn't have to be a two-gap player. Instead, he gets to challenge a single gap, which allows him to get more consistent penetration and generally cause havoc. That's the theory behind Grantham's take on the 3-4:
Note that the NT in this formation doesn't actually line up as a 0-tech; he's instead slightly offset at the strongside 1-tech. (He doesn't necessarily have to be there, but it's easier for illustrative purposes.) Because he's moved directly off center, he can easier challenge a single gap instead of the typical two-gap approach, meaning he'd go to either the left or right of center instead of right at him. That in turn forces the offense to respond differently than they would against a two-gap NT, and it's similar to how an offensive line copes with a DT in a 4-3. In addition, shifting the NT to a 1-tech in essenceforces the side that needs to double. Because the NT in the example above is shifted slightly, the left guard and center have to combine on the block (the right guard will never make it over there), and good things happen.
What kind of good things happen? Instead of being reliant on your NT soaking up two interior linemen, he directly threatens a gap, which in turn forces a hard response from the offensive line. The defensive end keeps the other guy on the line occupied, and the MLB on that side doesn't have to deal with any blockers. That means the MLB coming in gets to clean up the mess, and if he doesn't, then the OLB on that side gets to.
There's more than just that, though. Shifting the NT to single-gap allows you to do things like stunts, full-side overload blitzes (for example, in the above diagram the TE cannot release into his route if it's a pass play, otherwise it's four blitzers vs. three linemen and the QB gets peeled off the turf; If it's a run, all blockers are accounted for and the playside safety can easily snuff it out)